Dopaminergic agonist and cognitive function in Parkinson's disease

Background and Purpose: Disturbed cognitive function is a well recognized feature of idiopathic Parkinson's disease. Cognitive decline in Parkinson's disease patients has been observed in the domains of visuospatial capacity, memory and executive functions. Dopamine agonists have shown beneficial therapeutic effects on motor symptoms in Parkinson's disease, but their influence on cognitive functions is still controversial. The aim of this study is to evaluate the influence of dopamine agonists on cognitive functions in patients with Parkinson's disease. Materials and Methods: Two groups of idiopathic Parkinson's disease patients (7 patients in each group) were investigated during one year of treatment. The patients enrolled in the study Mere selected according to dopamine agonist medication. One group of patients was treated with levodopa and selegiline, and the other received the dopamine agonist bromocriptine in addition. Neuropsychological testing included Verbal Fluency Test and Hooper Visual Organization Test. Results: Both groups of patients demonstrated significant cognitive decline compared to age-matched controls (p <0.05) regarding executive function and visual integration. Although Parkinson's disease patients treated with bromocriptine were worse according to Hoehn and Yahr stage than those treated with levodopa, there were no differences in cognitive testing. Conclusion: Our results indicate the dissociation of specific cognitive functions and motor symptoms in Parkinson's disease. There was no evidence that the dopamine agonist bromocriptine improved cognitive functions in patients with Parkinson's disease. Our conclusions were limited by a small sample size and a relatively short period of treatment with dopamine agonists.